1. Field of the Invention
The present invention relates to a carrier tape feeder, and more specifically to an apparatus for continuous feeding of carrier tapes into a chip mounter.
2. Description of the Related Art
A chip mounter is an apparatus for high-speed, high-precision mounting electronic chips fed from a feeder on preset positions of a printed circuit board. In such a chip mounter, suction nozzles of a head are used to mount electronic chips. With the recent trend toward multifunctional, high-specification and downsized electronic devices, the need is increasing to develop techniques for mounting electronic chips in high density on printed circuit boards of the electronic devices. Technology for mounting chips on printed circuit boards is shifting from through-hole mounting to surface mounted technology (SMT). Surface mounted technology is used to directly mount chips in high density on the surface of printed circuit boards. Surface mounting devices (SMDs) for use in surface mounted technology are classified into tape roll, tray and stick types according to the feeding form of chips. Chip feeders are also classified into tape feeders, tray feeders and stick feeders by their chip feeding mode according to the type of surface mounting devices. Of these, the most widely used are tape feeders that feed chips in the form of carrier tapes. An advantage of tape feeders is the ability to feed a number of chips at high speed. A typical carrier tape consists of a base tape, storage spaces formed at regular pitches in the base tape and a cover tape attached to the upper surface of the base tape. Small-sized electronic chips, such as semiconductor chips, are accommodated in the storage spaces of the carrier tape. The cover tape is taped on the upper surface of base tape protects the electronic chips. Due to this construction, the carrier tape functions as a carrier to smoothly feed the electronic chips, such as semiconductor chips, into a chip mounter.
FIG. 1 illustrates (a) a state of a general carrier tape 100 in which a portion of a cover tape 102 is separated from a base tape 101, and (b) a cross-sectional view taken along line A-A′ of (a). Referring to FIG. 1, the carrier tape 100 consists of a base tape 101 and a cover tape 102 attached to the upper surface of the base tape 101. The base tape 101 is made of paper and has transport holes 103 formed at regular intervals at one lateral side thereof. The base tape 101 has storage spaces 104 with a predetermined depth to accommodate semiconductor chips (not shown) therein. The cover tape 102 is made of a transparent polymer film and is attached to the base tape 101 through adhesive portions 105 consisting of a first adhesive portion 105a and a second adhesive portion 105b. The carrier tape is generally wound on a reel for commercialization. While a tape feeder locks the transport holes of the base tape to move the carrier tape by specific pitches, the cover tape is separated from the base tape and the storage spaces are exposed so that the electronic chips can be picked-up by suction nozzles of a mounter.
A general carrier tape wound on a reel is fed into a carrier tape feeder. When electronic chips accommodated in the carrier tape are completely picked up, a new carrier tape reel must be loaded into the tape feeder. Since only one carrier tape reel can be loaded at a time into a general carrier tape feeder, a new carrier tape reel must be loaded into the carrier tape feeder after the carrier tapes are completely used up. Such loading process makes it impossible to continuously feed carrier tapes into the carrier tape feeder, causing prolonged working time. Further, an operator must watch the feeding state of the carrier tapes to check whether the carrier tapes are exhausted, which becomes a cause of deterioration in workability.
A general carrier tape feeder is designed such that base tapes and cover tapes are separately discharged after the cover tapes are completely separated from the base tapes. However, this design may cause entangling of the cover tapes to generate static electricity. Further, materials for the cover tapes may cause variations in the pitch of the carrier tapes in view of their characteristics, making it difficult to pick up electronic chips accurately. Several carrier tape feeders may be loaded on a chip mounter. This case may cause more serious static electricity problems because a larger number of cover tapes discharged from the tape feeders get entangled or come into contact with each other. Such static electricity problems may increase the number of defects or may lead to an increase in working time, giving a negative influence on productivity.